This invention relates to electric welding of parts together and more particularly to a method of and apparatus for removing an insulating surface layer or coating on one of the parts to effect metal-to-metal contact.
Various efforts have been made in the past to electrically weld metallic parts together through painted or insulation-coated surfaces, and exemplary of such are the techniques disclosed in the patents, to Ruetschi, U.S. Pat. No. 3,233,073 and Sweeney, U.S. Pat. No. 3,340,379. These patented methods required a mechanical disturbance of the coated surface, such as by puncturing or scraping the coating, to physically remove an intervening portion of the coating for establishing the metal-to-metal contact between the parts to be welded. Moreover, at the conclusion of the welding operation it was usually necessary to repaint or recoat the weld line to protect the welded connection against corrosion.